1. Field of the Invention
The present invention relates to an automatic analyzer for performing qualitative/quantitative analysis of biological samples such as blood and urine. More particularly, the present invention relates to reaction cuvettes in which a biological sample reacts with reagents and to an automatic analyzer equipped with these reaction cuvettes.
2. Description of the Related Art
In the field of clinical testing, with the increase in the test selection to a sample, the sample volume required to a single test decreases. As a result, samples are routinely analyzed in very small amounts. If the sample quantity for a single analysis can be further reduced, the quantity of reagent required for a single analysis can also be reduced, leading to reduction in costs as well. In addition, the quantity of waste liquid resulting from the analysis can also be reduced.
Along with the reduction in sample volume, progress is made toward reduction of reaction cuvettes in size (the reaction cuvettes are hereinafter referred to as reaction cells). However, the size reduction of a reaction cell also leads to reduction in the area in the reaction cell passed by the light from the photometer. As a result, the presence of bubbles in reacted sample liquid now becomes problematic, which could have been ignored in the conventional automatic analyzers. To be more specific, when a photometric light beam is directed to bubbles in a reacting sample liquid, the bubbles diffuse the light beam, adversely affecting the photometric analysis. In some cases, the photometry analysis itself may not be done.
In order to solve the above problem, Japanese Unexamined Patent Application Publication No. 2005-77263 (Patent Document 1) proposes a method for making the status of an inner surface of a reaction cuvette hydrophilic with the use of ozone treatments.
In addition, Japanese Unexamined Patent Application Publication No. 2006-125897 (Patent Document 2) proposes a method for performing surface treatment to the area passed by the photometric light beam and its vicinity of a reaction cell so that the hydrophilic properties (wettability) of only those regions are increased.